I only used a PSP for the similar size/ease of use. It would require much more work from me to create a portable 360 controller from scratch. :P I own a 360 and love the layout, this was just easier...

I believe for you to have any kind of feasible success...it would have to be an image that would apply to a large group. Like the tattoos, the sports logos, etc. More than just one person would have...